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yu zhou

code segment:

              ...
        EXTRN   NUMBER (MAX_NUM)


        DS      MAX_NUM


        END

another code segment:

        PUBLIC  MAX_NUM
        MAX_NUM EQU     8

when i assembled and linked these codes,
there was an error:

        Build target 'test'
assembling test.asm...
test.asm(13): error A28: ABSOLUTE EXPRESSION REQUIRED
Target not created

How did it hanppen?

Parents Reply Children
  • 0 in reply to John Linq

    I put the
    MAX_NUM EQU 8
    into the first file,not use the PUBLIC and EXTRN keywords to export and import the symbol!
    just like:

          MAX_NUM   EQU    8
...
      DS    MAX_NUM
...


    and then assembled and linked it,no errors!
    Why???

  • 0 in reply to yu zhou

    Why?

    Didn't you read the answers you got?

    "Look in the assembler manual what EQU means - it declares an assembly-time constant, not a run-time variable. The linker on the other hand processes run-time variables."

    PUBLIC and EXTRN are used for link-time symbols, not for assembly-time symbols. But your MAX_NUM is not a program variable that will be stored in any memory cell, and so will not be assigned any address by the linker.

    This is the same as programming in C:

    #define MAX_NUM 8


    or

    enum {
    MAX_NUM 8
};


    as compared to:

    int MAX_NUM = 8;

    Only the "int MAX_NUM" alternative will be a link-time symbol, where generated code reads from the memory to pick up the value.